The contamination was found in 48% of 120 chicken products bought in 10 major cities.

Dr. Michael Doyle, director of the Center for Food Safety at the University of Georgia, dismissed the findings because of the small sample size and because the kind of E. coli found was not considered a threat to public health.

“What’s surprising to me is that they didn’t find more,” Doyle told The New York Times. “Poop gets into your food, and not just into meat—produce is grown in soil fertilized with manure, and there’s E. coli in that, too.”

Between eight and nine billion chickens are killed for food each year in the United States.